It might be worth checking the wiring in your house, or having your amp checked out? Single coil J pickups will hum, but if you feel it is worse now than before then there might be another reason for this.
It would cost Fender more to produce noiseless pickups in this sort of volume. They might also want to change up the pots and cap specs while they are at it. All of this would be pushed onto the consumer. If Fender made a Mexican Standard Noiseless Jazz Bass then you can expect it to cost more. Beyond that, they would be changing up the Jazz bass formula, and probably a lot of Jazz players would be annoyed. I owned a set of 3rd gen Fender Noiseless Jazz pickups, and one of the pickups was dead on arrival. They were fragile, and used a fiddly circuitboard setup on the rear of the pickup to hook everything up. Other bassist have had the same problem with these pickups. I wouldn't necessarily want Fender to be making my noiseless pickups when Dimarzio, Seymour Duncan and Bartolini have been doing it with success, in some cases for several decades.
I think Dimarzio have done well with the Ultra Jazz pickup in this regard. Their three offerings cover quite a spectrum. The Area J is a pretty good stab at a reproduction '60s Jazz pickup set, the Model J is the oldschool 'muscle bass' pickup set from the '70s, and the Ultra Jazz is the more modern-sounding set with the extended low end and high end reproduction.
